We present the results of the empirical study that evaluates two quality attributes: performance and availability on three programs based on two architectural styles: the pipe-filter and the batch-sequential styles. The objective of this study is to identify what factors are crucial that might have the influences on these quality attributes from the software architecture perspective. It is hoped that this study is beneficial, so, early quality prediction can be facilitated from the analysis of the software architecture, furthermore, software developments can be improved significantly. The results from this study show that selecting a good architectural style based on variations in the execution environment to attain higher availability and/or better performance is feasible. Moreover, we demonstrate the effects of these variations on the quality measurements.